65,000,000.00 euros should be enough for the first vertical forest designed by Stefano Boeri‘s Milan-based studio.

Each of the four sides of the building will house 900 trees.

The same amount of trees, shrubs and plants in a garden would require 50,000 square meters of land, and 10,000 square meters of natural forest space.

Photovoltaic energy systems will contribute to self-sufficiency of the complex while grey water from the building will be filtered and reused for irrigation of the extensive flora. But I’m doubtful about two possible problems concerning wind:
One of them could be the uneven growth of the trees do to sail effect that could damages the backbone of the building strucrure.

I dare not imagine what would happen if, during summer, the irrigation system should fail, killing all the plants and the entire building could become a huge torch.